Attentional Guidance by Target-Location Probability Cueing Is Largely Inflexible, Long-Lasting, and Distinct From Inter-Trial Priming

There is growing consensus that selection history strongly guides spatial attention and is distinct from current goals and physical salience. Here, we focused on target-location probability cueing: when the target is more likely to appear in one region, search performance gradually improves for targets appearing in that region. Probability cueing is thought to reflect a long-lasting, inflexible and implicit attentional bias. However, strong evidence for these claims is lacking. We re-examined them in four experiments. The target was more likely to appear in one than in the other regions during the learning phase, whereas all regions were equiprobable during the extinction phase. We manipulated set size in all experiments. Probability cueing reduced search slopes during learning and extinction, suggesting that the bias is attentional and long-lasting. Although intertrial priming from several previous trials had an influence, it did not account for all the effects. We also found the bias to be largely inflexible: informing participants that the probability imbalance during learning would be discontinued during extinction did not reduce the bias. Moreover, the acquired bias remained the default determinant of attentional priority when goal-directed guidance failed (i.e., when a cue instructing participants to start their search in a given region during the extinction phase was omitted or invalid). Finally, many more participants than predicted by chance showed awareness of the probability manipulation, although we could not establish whether awareness was associated with the bias. We conclude that probability cueing is a long-lasting and inflexible attentional bias, distinct from intertrial priming.